Oil spills pose a major environmental threat to our increasingly urbanized world. Contamination of water and shoreline areas by even relatively modest amounts of oil can result in disastrous environmental consequences. In the environment, oil dissipates slowly over time and can cause significant adverse impacts for years unless cleaned up.
In response to an oil spill, clean-up personnel generally focus on cleaning up the spilled oil before the oil drifts ashore. Cleaning up an oil spill at sea dramatically reduces the risk of the spill impacting human population centers and other natural resources generally found in nearshore/shoreline environments. The adverse impact of an oil spill can thus often be significantly alleviated if the oil can be cleaned up before it reaches shoreline areas.
Cleaning up an oil slick floating on the surface of a body of water poses difficult problems. One attempted solution has been the use of ship-mounted oil containment and recovery systems (i.e., conventional booms and skimmers). Such recovery systems attempt to remove oil from the water's surface using direct suction devices, hydrodynamic planes, and a variety of oleophilic (oil-attracting) surfaces.
While satisfactory for some applications, such mechanical recovery systems generally require a great deal of logistical support, have relatively low oil recovery rates, and often pick up substantial volumes of water as well. The physical recovery of spilled oil with such skimming devices requires the use of large storage containers for the recovered oil and water, oil/water separation systems, and the provision of oil and oily waste disposal systems for the recovered fluids.
Many oil spill situations cannot be controlled adequately or in a timely manner with mechanical skimmers alone. The controlled burning of spilled oil in place (i.e., in-situ) with a fire-resistant boom provides an effective means of eliminating large volumes of oil quickly, with minimal logistical support, and without the need for large oil/water storage systems.
FIG. 1 illustrates spilled oil 20 floating on the surface of a body of water, being contained with a fire-resistant floating boom structure 22. Personnel maneuver the boom 22 into a shape corresponding generally to the letter "U", and contain and concentrate the spilled oil 20 (and/or other pollutants) between the legs of the U-shaped configuration. Once the oil has been sufficiently concentrated in the apex of the boom, personnel may ignite the oil using any of a number of aerial or surface ignition systems. The burning substantially consumes the oil, typically 90% to 98% of the contained oil, minimizing the risk of environmental damage. Unfortunately, the heat from the burning oil creates enormous thermal stress on the containment boom (typically 1800.degree. to 2000.degree. F.) which under wind and wave conditions may cause the rapid deterioration of even high temperature-resistant materials used in forming such booms.
Referring to FIG. 2, an oil containment boom 22 usually includes two main components: (i) a buoyant portion 24 extending above the water's surface 25 for flotation and to keep oil from splashing over the boom; and (2) a skirt or ballast portion 26 extending below the water's surface to prevent oil from escaping beneath the boom. Heat from the burning oil will typically impact the buoyant portion, and not the skirt/ballast portion as the skirt and ballast components generally remain submerged below the water's surface.
With continued reference to FIG. 2, one attempted solution for protecting fire-resistant containment booms from heat damage involves a cooling layer 28 in or between portions of the buoyant portion 24. The cooling layer is formed from a water absorbent material, in contact with the water. The cooling layer absorbs water, drawing moisture around the buoyant portion, against the influence of gravity, due to wicking. This moisture then functions for protecting the boom from heat.
While perhaps satisfactory in some applications, such passive cooling due to wicking generally provides insufficient heat protection. In particular, such passive cooling does not draw enough moisture, and/or does not draw the moisture upward far enough against gravity, along the buoyant portion to provide sufficient heat protection. That is, heat from burning oil still significantly damages such booms, even when the booms are made of high-temperature resistant materials. After use in an oil-burning operation, such booms normally require replacement and/or substantial repair.
The present invention provides an improved solution.